1. Field of the Invention
This invention relates to a continuous paper cutting unit for cutting perforated continuous paper along the line of perforations.
2. Related Art
A conventional continuous paper cutting unit is shown in FIG. 56 as described in Japanese Patent Laid-Open No. Hei 6-91588.
FIG. 56(a) depicts a continuous paper cutting unit 1. Continuous paper 2 having perforations engages a pin tractor 3 and is taken into the continuous paper cutting unit 1. The continuous paper 2 fed from the pin tractor 3 is transported by means of a paper feed roller 4 and a pinch roller 5 and is further transported past paper cutting boards 6 and 7, which also function as paper reception beds, by means of a paper discharge roller 8 and a pinch roller 9. The continuous paper 2 is transported so that its perforations are positioned in a gap between the boards 6 and 7, and the paper 2 is cut at the perforation position. The cut paper is transported one sheet at a time from the paper reception beds 6, 7 by the paper discharge roller 8 and the pinch roller 9 and stored in a stacker 10.
In the paper cutting portion of FIG. 56(b), shafts 11 each having a flange 18 penetrate paper pressers 12 and 12' and are fixedly secured to a cutter blade attachment member 13. A crank 15 attached to a drive shaft 14 transmits motion produced by rotation of the drive shaft 14 via a connecting rod 16 to the cutter blade attachment member 13. The motion produced by rotation of the drive shaft 14 is reciprocating motion in the vertical direction because a shaft 17 fixedly secured to a cabinet (see FIG. 56(e)) penetrates a hole of the cutter blade attachment member 13.
The paper pressers 12, 12' are supported by the flanges 18 of the shafts 11, and the cutter blade 19 and the paper pressers 12, 12' are at a sufficient distance from the paper reception beds 6, 7. At this point in time, the paper perforations are transported to the center of the gap between the paper reception beds 6 and 7 (see FIG. 56(c)). As the drive shaft 14 is rotated, the crank 15 rotates, thereby rotating the connecting rod 16 for lowering the cutter blade 19 which is fixedly secured to the cutter blade attachment member 13. As the cutter blade 19 falls, the shafts 11 also fall, so that the lower face of the paper pressers 12, 12' soon reach the paper reception beds 6, 7.
Although the paper pressers 12 and 12' abut the paper reception beds 6 and 7 and stop falling, the cutter blade 19 falls further while compressing springs 20, and the cutter blade 19 soon abuts the perforations of the paper 2, and tears the paper 2 along the perforations (see FIG. 56(d)). A large force acts on the paper 2 as the cutter blade 19 abuts the perforations, but the paper pressers 12 and 12' press the paper due to-the repulsion of the spring 20. Thus, the paper 2 is not brought into the gap between the paper reception beds 6 and 7 and the cutter blade 19.
As the drive shaft 14 rotates, the cutter blade 19 rises and soon the paper pressers 12 and 12' are pulled up. Then, the paper feed roller 4 and the paper discharge roller 8 rotate to feed the cut paper 2 into the stacker 10 and transport the subsequent portion of continuous paper 2 forward to a predetermined position. The operational sequence is then repeated.
Japanese Patent Laid-Open No. Sho 50-96136 is an example of another conventional continuous paper cutting unit, and is shown in FIG. 57. In FIG. 57(a), paper reception beds 21, 22 are placed on a paper discharge passage of a line printer, and continuous paper 2 is discharged from the line printer and guided to the reception beds 21, 22.
Up and down movable paper retainers 23, 24 which act as paper pressers, each having a flat friction face, are pressed down, as required, such that perforations 2a of the continuous paper 2 are positioned at a substantial center of a gap between the paper reception beds 21 and 22. The retainers 23, 24 press both sides of the perforations 2a of the continuous paper 2 against their respective reception bed faces 21, 22 throughout the paper width. The retainers 23 and 24 have rubber pieces 23a and 24a for providing a flat friction face at the tip of the retainers 23, 24.
To cut the paper 2 along the perforations 2a, the paper may be struck at the center throughout the paper width with an up and down movable plate-like blunt instrument 25, which is rounded at the tip 25a, such that both sides of the perforations 2a of the continuous paper 2 are sandwiched between the retainers 23 and 24 and the reception beds 21 and 22.
As shown in FIG. 57(b), a device having a rounded tip 25a shaped like a slope is used as the blunt instrument 25. Since such a blunt instrument would start to press the paper at a lowermost end part 25a', the act of cutting the paper is started at one end of the perforations 2a by using the lowermost end part 25a' of the blunt instrument 25, as shown in FIG. 57(d), to strike against the perforations 2a. Therefore, ten paper cutting proceeds from one end of the perforations to the other end as the paper is torn off along the perforations, so that the paper can be cut smoothly.
In Japanese Patent Laid-Open No. Sho 50-96136, a rod 26 pivoting about one point 26c as it is swung downward is also disclosed as a blunt instrument, as shown in FIG. 57(c).
Problem 1
In the conventional continuous paper cutting unit shown in FIG. 56, after the paper pressers 12 and 12' abut the paper reception beds 6 and 7 and stop dropping, the cutter blade 19 must have fallen to the cutting position while the spring 20 is being compressed. Thus, a large drive force is required to lower the cutter blade 19. That is, a large drive force is required at cutting time.
Problem 2
In the conventional continuous paper cutting unit shown in FIG. 56, when the continuous paper 2 is fed or transported to the cutting unit, the edge of the continuous paper 2 easily strikes against the side face of the paper presser 12 or 12', thus a paper jam easily occurs.
Likewise, also in the conventional continuous paper cutting unit shown in FIG. 57, when the continuous paper 2 is fed or transported to the cutting unit, the edge of the continuous paper 2 easily strikes against the side face of the paper retainers 23 or 24, and a paper jam easily occurs.
That is, in both the conventional cutting units, it is hard to produce a smooth feed or transport state of continuous paper.
Problem 3
In both the conventional continuous paper cutting units, when continuous paper 2 is transported, the gap between the paper reception beds 6 and 7 (see FIG. 56(b)) or the gap between the reception beds 21 and 22 (see FIG. 57(a)) is open.
Thus, when continuous paper 2 is transported, it enters the gap, easily causing a paper jam to occur.
Problem 4
In the conventional continuous paper cutting unit shown in FIG. 56, when the continuous paper 2 is transported, a lower end 19a of the cutter blade 19 is positioned somewhat above the lower face (12'a) of the paper presser 12, 12', as seen in FIG. 56(b).
Therefore, when the continuous paper 2 is supplied to the cutting unit, the edge of the continuous paper 2 easily enters the gap between the paper pressers 12 and 12' (below the cutter blade 19), thus a paper jam easily occurs.
In the conventional cutting unit shown in FIG. 57, the opposed face 25a of the blunt instrument 25 to the continuous paper 2 is inclined as seen in FIG. 57(b), thus when the continuous paper 2 is transported, a part of the blunt instrument (at least the lowermost end part 25a') projects downward below the lower faces of the retainers 23 and 24, and other parts (at least the uppermost end part) are positioned somewhat above the lower faces of the retainers 23 and 24 as seen in FIG. 57(a). Alternatively, assuming that a part of the blunt instrument 25 does not project downward below the lower faces of the retainers 23 and 24, the opposed face 25a of the blunt instrument 25 to the continuous paper 2 is positioned in most portions somewhat above the lower faces of the retainers 23 and 24. The same goes for the blunt instrument 26 shown in FIG. 57(c).
Therefore, in the conventional cutting unit shown in FIG. 57, when the continuous paper 2 is supplied to the cutting unit, one side of the edge of the continuous paper 2 easily strikes against the portion of the blunt instrument 25 positioned below the lower faces of the retainers 23 and 24 (for example, near the lowermost end part 25a'). Alternatively, the other side of the edge of the continuous paper 2 easily enters the gap between the retainers 23 and 24 (below the blunt instrument). Thus, a paper jam easily occurs.
That is, in both the conventional cutting units, it is hard to produce a smooth feed state of continuous paper.
Problem 5
In the conventional continuous paper cutting unit shown in FIG. 56, the edge of the continuous paper 2 after being cut comes in contact with the rising cutter blade 19, curls upward, and easily strikes against the side face of the paper presser 12' placed downstream.
Likewise, also in the conventional continuous paper cutting unit shown in FIG. 57, the edge of the continuous paper 2 after being cut, comes in contact with the rising blunt instrument 25 (or 26), curls upward, and easily strikes against the side face of the retainer 24 placed downstream. Particularly, the opposed face 25a of the blunt instrument 25 to the continuous paper is inclined and the upper end part is positioned somewhat above the lower faces of the retainers 23 and 24, thus in the gap portion, the edge of the continuous paper curls up, for example, and easily strikes against the side face of the retainer 24 placed downstream.
That is, in both the conventional cutting units, it is hard to produce a smooth feed or transport state of continuous paper after cutting.
Problem 6
According to the conventional continuous paper cutting unit shown in FIG. 57, cutting of continuous paper 2 is started at one end of the perforations 2a (the left end in FIG. 57(c), namely, the cutting start part) and proceeds toward the other end (the right end in FIG. 57(c), namely, the cutting end part). Thus, unless the paper is pressed reliably from the cutting start part to the cutting end part, a smooth cutting operation is not achieved. Particularly, a large press force is required at the cutting start time, namely, at the cutting start part.
Further, the continuous paper 2 may have perforations 2a made to a side end margin 2b of the paper 2 as shown in FIG. 58(a) or may have perforations 2a that do not reach the side end margin 2b of the paper 2 as shown in FIG. 58(b). Accordingly, in order to cut the continuous paper 2 having perforations that do not reach the side end margin 2b as shown in FIG. 58(b), a still larger press force is required at paper cutting time.
No solutions to this problem are disclosed in Japanese Patent Laid-Open No. Sho 50-96136.
Problem 7
According to the conventional continuous paper cutting unit shown in FIG. 57, the continuous paper 2 is cut starting at one end of the perforations 2a (the left end in FIG. 57(c), namely, the cutting start part) and proceeds toward the other end (the right end in FIG. 57(c), namely, the cutting end part). Thus, the paper 2 is comparatively hard to cut at the cutting start part for the reasons stated above. However, once the cutting is started, comparatively smooth cutting proceeds.
On the other hand, as described above, the continuous paper 2 may have perforations 2a made to the side end margin 2b of the paper as shown in FIG. 58(a) or may have perforations 2a that do not reach the side end margin 2b as shown in FIG. 58(b). Therefore, the continuous paper 2 having the perforations that do not reach the side end margin 2b as shown in FIG. 58(b), is hard to cut, particularly in the cutting start part. The continuous paper 2 having perforations 2a made to the side end margin 2b of the paper as shown in FIG. 58(a) is easy to cut in the cutting start part as compared with the continuous paper having perforations that do not reach the side end margin 2b as shown in FIG. 58(b), but remains hard to cut in the cutting start part as compared with the subsequent cutting.
No solutions to the problem are disclosed in Japanese Patent Laid-Open No. Sho 50-96136.
Problem 8
To cut continuous paper reliably in this kind of continuous paper cutting unit 1, the continuous paper 2 must be held reliably.
Problem 9
Usually, continuous paper having perforations is often folded in zigzags (side view) at the perforations (see FIG. 56(a)).
Thus, the folds may remain impressed in the paper 2 after the continuous paper 2 is transported to the inside of the cutting unit 1, and the continuous paper 2 may become deformed and have a convex or concave appearance at the perforations.
Under these circumstances, if the continuous paper 2 is simply pressed and held on both sides of the perforations 2a, the paper 2 still remains deformed. Therefore, at cutting time, the continuous paper 2 is loose due to deformation and becomes hard to cut.
Problem 10
When the continuous paper 2 is cut as shown in FIG. 57(d) in the conventional continuous paper cutting unit as shown in FIG. 57, a fold 2c may be left impressed in the continuous paper 2. Such a fold easily remains impressed in the paper 2 particularly when the perforations 2a shift largely from the center as indicated by 2a' in FIG. 57(a).
If an attempt is made to transport the continuous paper 2 to the right after cutting as shown in FIG. 57(d), for example, with the fold 2c remaining in the paper 2, the edge of the continuous paper 2 at the perforation 2a strikes against a side face 22a of the paper reception bed 22 located downstream in the paper transport direction, so that a paper jam may occur.